We propose to apply molecular biological techniques towards an understanding of some aspects of the biology of the parasites causing lymphatic filariasis, and at the same time determine the structure of antigenic molecules that might be important in protective immunity. The specific objectives will be: 1. ANALYSIS OF MOULTING: We will clone the genes encoding moulting enzymes, by exploiting the conservation of physiology and biochemistry of the process of moulting among nematodes. These genes will be used to study the enzymology of moulting, the regulation of synthesis of these enzymes and potential strategies for interfering with this process. The goal of this set of experiments is to determine whether specific immunization against moulting enzymes is a viable strategy for blocking morphogenesis of the filarial parasites. 2. ANALYSIS OF CUTICULAR COLLAGENS: We will use a partial collagen gene we have recently cloned to isolate full length collagen genes and analyze their stage-specific expression and sequence diversity. The goal of this set of experiments is two fold: first to define whether there are any collagens that are specific for the L3 and L4 stages of the parasite and second to determine nematode specific sequences that are not shared with mammalian collagen. Immunization with L3 and/or L4 specific collagen sequences that are structrually different from host collagen may be effective means of eliciting protective immunity without the danger of autoimmune responses. 3. CLONING GENES FOR PROTECTIVE ANTIGENS: We will screen cDNA and genomic expression libraries derived from the human filarial parasite B. malayi with sera from patients suffering from a wide spectrum of filarial disease to isolate genes encoding protective antigens. We have used a serum from a patient suffering from Tropical Pulmonary Eosinophilia (TPE) to isolate several reactive gt-11 clones and have sequenced the inserts in two of them. These studies will be extended during the tenure of this proposal.